So I used elmers glue and added fine gravel to one base. The 2nd base are egg shells and painted a lava like base. Would added a clear coat help with its longevity of dirt/egg shells not peeling off over time?
Short answer, Yes. Yes it would. 
probably. i never do it but that doesn’t mean it shouldn’t be done.[:D]
but then i never put a barrier coat between my paint and my washes so WTH.